Pushbutton switch with coil spring contacts

ABSTRACT

An electrical switch in which contacts are comprised of portions of two concentric, current conductive springs. One of the springs has an open end and the other of the springs has an end that is closed by the presence of a conductive portion extending thereacross. Linear movement of one spring with respect to the other causes the edge portions of the open ended spring to engage the conductive portions at radially spaced apart positions on the other spring to provide at least two conductive contact areas. A mounted assembly may provide a base for holding the springs in a predetermined initial position and relationship and a mounting for an actuator for imparting motion to at least one of the springs.

[451 Nov. 20, 1973 PUSHBUTTON SWITCH WITH COIL SPRING CONTACTS [75] Inventor: Keith A. Shari, Santa Ana, Calif.

[73] Assignee: Controls Research Corporation,

Santa Ana, Calif.

22 Filed: May 20, 1971 21 Appl.No.: 145,283

Primary ExaminerRobert K. Schaeffer Assistant Examiner-Robert A. Vanderhye Attorney-Carlsen, Carlsen & Storm [5 7] ABSTRACT An electrical switch in which contacts are comprised of portions of two concentric, current conductive springs. One of the springs has an open end and the [52] US. Cl. 200/159 R, ZOO/166 BA other of the springs has an end that is closed by the 1] llll- L Holh Holh /3 l presence of a conductive portion extending therel Field of Search 5 166 across. Linear movement of one spring with respect to ZOO/77 the other causes the edge portions of the open ended spring to engage the conductive portions at radially [56] R nc s Cited spaced apart positions on the other spring to provide UNITED STATES PATENTS at least two conductive contact areas. 3,435,165 3/1969 Lombard 200/166 BA UX A mounted assembly may provide a base for holding 2,440,288 4/1948 Paulus et a1... 200/ 159 R the springs in a predetermined initial position and 667,764 2/1901 B11166 200/77 r lationship and a mounting for an actuator for 2,444,552 7/1948 Brantmgson 200/ 166 BA X imparting motion to at least one of the springs FOREIGN PATENTS OR APPLICATIONS 872,773 5 1941 France 200/166 BA 2 8 Fgures I 1 l l l I t 5/ PAIENIED NOV 20 ms llllll llll llll FIE 5 "IHI'I "HIM n. M O

W I L INVENTOR. 4 5776 4. 5/2 42 MM SZT/a 4 rraewsy PUSIIBUTTON SWITCH WITH COIL SPRING CONTACTS DESCRIPTION OF THE INVENTION The continued expansion of the use of electrical switches in business machines, typewriters, computers and the like has resulted in the development of new and better switching apparatus for reliably, efficiently, and economically providing the necessary plurality of automatic or manually operated switching functions that may be required. Examples of prior art devices include the normal contact assemblies in which a pair of contacts are caused to move into conductive engagement in a manner familiar to those skilled in the art, for a considerable time. The prior art is replete with many other forms of contact assemblies which may be actuated by various forms of energy, such as, for example, sealed in glass reed contacts that may be magnetically actuated.

As the requirements for improved reliability, efficiency, and the like have increased, the cost of providing such switches has also increased. One of the advantages of my invention is its relatively low cost with respect to its performance characteristics.

In one preferred embodiment of my invention, a pair of concentric compression springs are suitably mounted upon a base and provisions are made for linear movement of one of the springs with respect to the other to effect actuation thereof.

A round inner spring is provided with a configuration at one end that is mounted and retained in a base member and a configuration at its top end that forms an open-ended cylindrical edge portion. A larger round outer spring is also provided with a means at one end that is mounted on the same base member so that it is disposed concentrically of the inner spring and may be of roughly twice the diameter of the inner spring. The other, or free end of the larger outer coil spring is provided with a portion extending thereacross and roughly perpendicular to its longitudinal axis. As the free end of the outer spring is caused to move toward the free, cylindrically shaped end of the inner spring, a dual contact is effected whereby the top cylindrical end of the inner spring is engaged at two radially spaced points of contact as the relative movement and displacement of the free end of the larger outer spring causes some axial movement of the top open cylindrical end of the inner spring. Preferably, the entire spring assembly is comprised of material exhibiting suitable'current conductive properties and suitable spring characteristics.

It is an object of this invention to provide an improved electrical switch contact apparatus.

A still further object of my invention is to provide an improved contact apparatus which incorporates a pair of concentric coil springs with means extending radially of one of the coil springs for contacting the other of the coil springs at at least two radially spaced points.

A still further object of my invention is to provide an improved push button switch assembly in which one of a pair of contacts is utilized to initially position an actuator therefor.

These and other objects of my invention will become apparent from a consideration of the appended specification, claims and drawing for which:

FIGS. 1 and 2 are a front and top plan view of a partially completed push button switch assembly incorpo rating the principles of my invention;

FIG. 3 is an enlarged fragmentary sectional view of the apparatus shown in FIGS. 1 and 2 taken along section line 3-3 on FIG. 2;

FIG. 4 is an enlarged fragmentary sectional view of another portion of the apparatus shown in FIGS. 1 and 2 taken along section line 44 on FIG. 1 of the drawmgs;

FIG. 5 is an enlarged perspective sketch showing the relationship of the two concentric coil springs of the contact assembly utilized in FIGS. 1, 2, 3 and 4; and

FIGS. 6, 7 and 8 are side views, partially in section, illustrating the operation of a further embodiment (which embodies the preferred embodiment shown in FIGS. 1-5) of my invention in various stages of a cycle of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the several views of the drawings in which like elements have been identified by like reference characters, the assembled apparatus of FIGS. 1 and 2 is shown to include an upper body member 41 which is provided with a plurality (six) of interiorly disposed chambers cylindrical 40, each of which has a smaller generally square, upwardly opening aperature 42 (including a peripheral boss) at the top end thereof,

through which may extend a plurality of plungers 30. Plungers 30 include a top mounted push button 34 and a top intermediate section 31, of like square cross section to apertures 42, and extending therethrough to chambers 40 in body 41. A base member 50 is shown disposed on the bottom portion of body member 40 and includes a like plurality (six) of areas, each of which is provided with a large diameter boss 51 and a small diameter boss 52 (for purposes to be described below) and a pair of downwardly opening apertures 53 and 54. Each of the areas is disposed under a corresponding chamber 40 in body member 41.

Plunger 30 is shown in, for example, FIG. 3 of the drawings, as comprising a top portion 31 that is square and may extend through apertures 42 in body member 41 and a lower round bottom portion 32 which has a round, tapered, downwardly opening recess 33 slidably disposed in chamber 40.

A switch contact assembly comprised of an inner spring member 10 and an outer spring member 20 is shown disposed within chambers 40 in body member 41 and mounted upon base member 50 within boss members 51 and 52 so as to be disposed generally as illustrated in the drawings.

Inner spring 10 is comprised of material exhibiting suitable spring characteristics and desirable current conductive cylindrical in shape and is open ended. The

other, lower end of inner spring is provided with a 3 downwardly extending terminal portion 12 that is shown extending through an aperture, 54, in the bottom of the base member 50 in FIG. 1 of the drawings.

Outer spring 20 is shown having a generally cylindrical configuration and has a portion of the spring material extending across substantially a diameter of the top end 21 and generally perpendicular to the longitudinal axis thereof. This cross member 22, it will be seen below, together with the cylindrical top end of inner spring 10, will define a pair of contact points 24 and 25 when the two springs are in engagement as illustrated on FIGS. 4 and 8 of the drawings. Spring 20 is also provided with a downwardly extending terminal 23 at the lower end thereof which extends through a corresponding aperture, 53, in base member 50. It may be seen that terminals 12 and 23 on the respective spring members may be suitably connected to an electrical circuit to perform a desired switching function.

In operation, the initial starting point for the illustrated embodiment is that in which the plunger 30 is biased toward its upper-most position through the influence of the biasing force exhibited by the compressional force of outer spring 20. Outer spring member 20 is disposed concentrically outwardly of inner spring and both are securely disposed and mounted within chamber 40 by coaction with the boss members 51 and 52 and apertures 53 and 54 on the suitably situated areas of base member 50. As a linear downward force is exerted on push button 34 on plunger 30, the top of outer spring is moved downwardly and cross member 22 will come into contact with the top open end cylindrical element, 11, of inner spring 10. It may contact one or the other ends of the top 11 of inner spring 10 but as the force is continued to be applied, full, conductive contact will occur at each of contact points 24 and 25. The reverse operation takes place when the force is removed from push button 34 .on the top of plunger 30 and the upwardly biasing force exerted by outer spring 20 causes plunger 30 to move upwardly to cause disengagement of cross member 22 from the top edges of top 11 on inner spring 10 to open the contact assembly.

In the embodiment illustrated in FIGS. 6, 7 and 8, an additional bump45 has been provided over at least a portion of the periphery of chamber 40 so that a snap action may be obtained. Initially the downward motion of outer spring 30 is resisted because its sides may be in engagement with bump 45 extending inwardly of chamber 20. When sufficient force to cause inward deformation of outer spring 20 is supplied, the top end of spring 20 will become disengaged from bump 45 and will proceed rapidly downwardly into engagement with the cylindrical open top H on inner spring 10 so that rapid and complete actuation may take place. The relative disposition of the bumps 45 or other forms of mechanical, electrical or magnetic detents are left to the imagination of those skilled in the art once the principles of my invention are fully understood.

One other aspect of my invention which is not illustrated in the drawings, might be the provision of other forms of contacts which could provide the dual points of contact between inner and outer springs 11 at points corresponding to'those illustrated generally by reference characters 24 and 25 on FIGS. 4 and 8 of the drawings. One form such apparatus could take would be to place cross member 22 across corresponding axially intermediate points on the periphery of outer spring 20 so as to dispose the points of contact intermediate the ends thereof whereby, for example, the operation of the detent or the like operation provided by the bump in FIGS. 6, 7 and 8 of the drawings might be enhanced since an intermediate portion of outer spring 20 could be engaged by the bumps so that the spring rate existing on the top of outer spring 20 could be applied with a sudden movement to further contribute to the snap action operation of the assembly.

It may also be noted that in a somewhat similar manner, cross member 22, which is shown disposed on the top of outer spring 20 in the illustrated preferred embodiment, could likewise be disposed across the top of inner spring 10 and mounted thereupon by suitable current conductive means so that upon similar relative linear movement axially of one spring with respect to the other, a pair of contacts 24 and 25 would be effected upon actuation. For example, if the relative axial length of the spring member l0 and 20 were reversed so that inner spring 10 was normally substantially longer than outer spring 20, downward movement of inner spring 10 would result in conductive engagement with outer spring 20 where cross member 22 had previously been removed from the top of outer spring 20 and a similarly dimensioned cross member had been applied and conductively connected and disposed on the top end of inner spring 10.

It has been determined that the springs may be comprised of suitable conductive material, but in a preferred embodiment, a phosphorus bronze material has proven to exhibit conductive and spring rate characteristics which result in satisfactory operation of a working model.

Having now therefore fully illustrated and described my invention, which I claim to be new and desire to protect by Letters Patent is:

1. In apparatus of the class above described, the combination comprising;

a. an elongated hollow housing;

b. first spring means having one end mounted on one end of said housing, and the other end disposed intermediate the ends of said housing;

c. second spring means having one end mounted on said one end of said housing, the other end disposed in proximity to the other end of said housing;

(1. one of said spring means including a prtion extending radially across the other of said spring means for less than the entire periphery of said one of said spring means intermediate the ends of said one of said spring means, whereby relative axial movement therebetween causes conductive engagement of said portion on said one of said spring means with the other of said spring means; and

e. actuating means operable to axially displace at least one of said spring means whereby conductive engagement intermediate said radially extending portion and the other of the spring means is effected.

2. In apparatus of the class above described, the combination comprising,

a. an elongated hollow housing;

b. first spring means having one end mounted on one end of said housing, and the other end disposed intermediate the ends of said housing;

c. second spring means having one end mounted on said one end of said housing; the other end disposed in proximity to the other end of said housing and of larger diameter than said first spring means;

(I. said first spring means including a portion extending radially across said second spring means for less than the entire periphery of said first spring means whereby relative axial movement therebetween causes conductive engagement of said portion on said first spring means with said second spring means; and

e. actuating means operative to axially displace at least one of said spring means whereby conductive engagement intermediate said radially extending portion on said first spring means and said second 

1. In apparatus of the class above described, the combination comprising; a. an elongated hollow housing; b. first spring means having one end mounted on one end of said housing, and the other end disposed intermediate the ends of said housing; c. second spring means having one end mounted on said one end of said housing, the other end disposed in proximity to the other end of said housing; d. one of said spring means including a prtion extending radially across the other of said spring means for less than the entire periphery of said one of said spring means intermediate the ends of said one of said spring means, whereby relative axial movement therebetween causes conductive engagement of said portion on said one of said spring means with the other of said spring means; and e. actuating means operable to axially displace at least one of said spring means whereby conductive engagement intermediate said radially extending portion and the other of the spring means is effected.
 2. In apparatus of the class above described, the combination comprising; a. an elongated hollow housing; b. first spring means having one end mounted on one end of said housing, and the other end disposed intermediate the ends of said housing; c. second spring means having one end mounted on said one end of said housing; the other end disposed in proximity to the other end of said housing and of larger diameter than said first spring means; d. said first spring means including a portion extending radially across said second spring means for less than the entire periphery of said first spring means whereby relative axial movement therebetween causes conductive engagement of said portion on said first spring means with said second spring means; and e. actuating means operative to axially displace at least one of said spring means whereby conductive engagement intermediate said radially extending portion on said first spring means and said second spring means is effected. 